Until recently, most hard drives connected with USB 2.0 or USB 3.0 connections, but now many are moving over to USB-C, which offers 10 Gps of transfer speed, equivalent to twice the speed on offer from USB 3.0. Other forms of connection include wireless transfer to the hard drive.
Although hard drives tend to be pretty reliable there are few comprehensive reviews of how reliable drives are over a long time under strain, and nobody wants to loose years of cherished photos or videos.
Data from Backblaze shows Hitachi and Western Digital drives had some of the lowest failure rates last year, although these stats are largely limited to internal drives. To keep your files safe you may want to buy a more rugged hard drive.
Write and read speed
Read speed is essentially how long it takes to upload files from your head drive, while write speed is how long it takes to save something to the drive.
Most cheaper hard drives will have a fairly modest read/write speed of around 100 to 150 MB per second, not brilliant if you want to load or transfer lots of large video files.
Better hard drives will offer zippier speeds of 400 MB per second or better, although the prices will start to stack up at this range.
The price of an external hard drive can vary from anything between £50 to £250 for medium sized drives of between 1 TB and 4 TB. More expensive, faster hard drives can cost £250 or more, while seriously large and powerful hard drives can cost several hundred pounds.
You can also get external SSDs. These will cost more for the storage space, so a medium sized SSD of around 1 TB will be significantly more expensive than a hard drive of a similar size.